But in a similar case, the court ordered the US to stay the execution of a German national in 1999 - he was put to death nevertheless.

The current case has put pressure on Mexico to reform its own justice system.

Hours before the judgement, Mexico's President Vicente Fox announced a reform package that includes plans to substitute the death penalty, which exists for military personnel, with 30- to 60-year prison sentences.

The death penalty has not been applied in Mexico's army
since 1961 and is theoretically reserved for the worst
offences, such as treason or serious dereliction, the Associated Press reported.